The present invention relates to an image processing system, being capable of designating a recording position, which can enlarge and reduce an original image by using data interpolation and can arbitrarily designate the position on a recording paper where the image is recorded.
The invention relates to an image processing system which enlarges and reduces the information of an original draft by interpolation, and in particular to an image processing system being capable of changing the contents of an interpolation table in accordance with the characteristics of an image.
The invention relates to a color image recording system, being applicable to simple electrophotographic color copying machines and the like, and being capable of enlarging and reducing an image in a specified color.
With an image processing system being capable of enlarging and reducing an original image, the output devices such as a display, recording device and the like usually display or record the image comprising only two types of binary codes respectively representing "black" and "white".
As a method to represent pseudo-halftone with such output devices, the dither method and the like are known in the art. The dither method is one type of area gradation method, and represents an halftone image by varying the quantity of dots being recording in a specific area (matrix).
Accordingly, in the dither method, an area corresponding with one pixel in an original draft is recorded as one dot, by using a specific threshold value matrix as shown in FIG. 45. By this arrangment, binary coded output data are available. Such output data represent a pseudo-halftone image in the two types of binary data, "white" and "black".
Of color image processing systems having such a type of output devices, the similar systems being capable of recording, through enlarging or reducing operation with an externally designated magnification, an original image obtained via an image reading means such as CCD or the like have been developed.
With these systems, an enlarged or reduced image, as required, is obtained principally by varying the frequency of a clock signal (transfer clock signal) for image reading, by a CCD in accordance with a magnification.
With an output device, if a scanning time needed for scanning one line in the main scanning direction is TW, and if the number of pixels involved for scanning one line is N, the frequency of transfer clock signal f0 of the device is expressed, below; EQU F0=N/TW
Similarly, if the frequency of transfer clock signal from a CCD is f, and if the time needed for the CCD to scan one line is T, then; EQU f=N/T
Accordingly, when f&gt;f0, an original image is recorded through reduction, and when f&lt;f0, the image is recorded through enlargement.
The above-mentioned conventional image processing systems, however, have the following disadvantages, since they involve the transfer clock signal, for a CCD, whose frequency can be varied in accordance with a magnification.
Firstly, because of an arrangement to vary the transfer clock signal being fed into the CCD, the control for not only the transfer clock signal but the exposure of an exposing lamp is required. Accordingly, it is necessary to incorporate a circuit for controlling the exposure.
Additionally, as the frequency of transfer clock signal being fed into the CCD must be varied in correspondence with a magnification, it is also necessary to use a variable type clock signal generator. In this case, if an arrangement to set a magnification in greater precision is incorporated, the frequency of transfer clock signal must be regulated with higher precision, resulting in a complicated circuit in the variable type clock signal generator.
Furthermore, varying the transfer clock, which is fed into the CCD, in accordance with a magnification is tantamount to varying the sampling position, in relation to an original image, in accordance with the magnification. Accordingly, the same data corresponding to the same sampling position of an original image are repeatedly used in the enlarging operation, and, in contrast, a part of the data is thinned out in the reducing operation. As a disadvantageous result, a recorded image which is an exact enlargement or reduction of an original image cannot be obtained.
On top of this, the method fails to provide a recorded image having satisfactory quality, because the enlarging and reducing operations are carried out simply based on the data sampling.
To eliminate such disadvantages, an enlarged or reduced image is produced by adding or thinning out the data related to a pair of adjacent image data, on the basis of levels of these neighboring data, after an original image data are generated.
For this purpose, the inventors have proposed an interpolation method, wherein the enlarging and reducing operations are carried out, by previously providing interpolation data within a ROM in order to interpolate the data between neighboring pixels within the read-out image information, and by reading out the above-mentioned interpolation data, based on both the read-out image data and the interpolation data selection data corresponding with the predetermined magnification.
Involving no need for varying a transfer clock signal in accordance with a magnification, this method eliminates a complicated clock generating circuit, and does not need the control of exposure, and can provide a high quality image.
This method, however, having only one type of interpolation table where data for interpolation is stored, cannot realize an image quality suitable for representing characteristics of original draft, that is, whether the draft is of a line drawing, photograph or the like.
The object of the invention is, in order to give the solution to the above-mentioned disadvantages, to provide an image processing system which can produce processed image with an excellent quality by satisfactorily emphasizing the edges in a line drawing or by giving sufficient tone representation in a photograph.
Furthermore, for such type of data interpolation, the image data (interpolation data) in accordance with a sampling position corresponding with a magnification must be provided as a ROM table. Setting a magnification to a higher precision or obtaining a good image quality which corresponds to the characteristic of the original accordingly requires an increased amount of data provided in the ROM table, resulting in a large capacity memory and hence an increased cost.
Therefore, it is an object of the present invention to eliminate the disadvantages of conventional image processing systems, that is, a complicated peripheral circuitry for enlarging and reducing, as well as a deteriorated quality of recorded image, and to provide an image processing system, being capable of enlarging and reducing operations, which realizes a smaller size of interpolation table even if such a system generates interpolation data for enlarging and reducing operations by interpolation methods.
As stated above, of color image processing systems having output devices, those having the features to record an original image via enlarging and reducing operations with an externally designated magnification have been developed. These systems generate signals corresponding to an enlarged or reduced image by adding or thinning out appropriate image data, in accordance with a magnification, to or from image data of an original image being read with an image reading means, such as a CCD.
However, such enlarging and reducing operations only treat binary coded image signal. In another method, a signal transmitted from a CCD and processed for enlarging or reducing is separated into a plurality of color signals necessary for recording a colored image.
The above-mentioned conventional color image processing systems, however, produce an image of significantly deteriorated quality, since they carry out image processing, such as an enlarging or reducing operation, based on binary coded image data.
More specifically, in an enlarging or reducing operation, which is an image processing to add or thin out image data, the data solely comprising "1"s and "0"s are added to or thinned out from binary coded image data. Accordingly, when an image, for example, an oblique line, is enlarged, the ruggedness in an enlarged image is emphasized.
If an image processing, such as an enlarging or reducing, is carried out prior to the separation into a plurality of color signals, the color separation properties may deteriorate depending on a designated magnification, or, in the worst case, the color separation characteristics must be changed, in accordance with a magnification.
This is because the separation of an original color image into a plurality of color signals is effected by selecting specific colors with reference to a color separation map which stores the color separation data for the equal scale ratio. Accordingly, it is impossible to refer to the color data corresponding to the original color image when a non-equal magnification, that is, a magnification for enlarging or reducing is used.
Naturally, the color separation properties deteriorate if only one color separation map is used. If a plurality of color separation maps respectively corresponding to each magnification are provided, complicated control system for the maps are required.
Therefore, the present invention provides a color image processing system being capable of enlarging and reducing operations, which does not cause the quality of a recorded image to deteriorate or the color separation properties to degrade.
As also stated above, with an image processing system being capable of enlarging and reducing an original image, if a photoelectric conversion element such as a CCD is used as an image reading means, the image signal with enlargement or reduction incorporated is obtained usually by adding to or thinning out from the image pixel data of the original image being read with the photoelectric conversion element, in accordance with an enlarging or reducing magnification.
FIG. 38 is a schematic diagram illustrating one example of the principal area of a processing system being capable of enlarging and reducing operations and being used in such an image processing system.
In this figure, numeral 40 is a memory for image data. Into an input terminal 41 of the memory 40, the image data read by an image reading means are fed after incorporating enlarging or reducing. The output image data transmitted from an output terminal 42 are fed into a recording device and the like, where the enlarged or reduced image is reproduced.
In an enlarging or reducing operation, the amount of image data transmitted to the memory 40 is limited by the recording width of a recording device. In this case, the generating timing of address signal generated by an address signal generator 47 and fed into the memory 40 is controlled in accordance with the operation mode, whether an enlarging or reducing operation.
For controlling this timing, first and second counters 43 and 44 capable of presetting are provided. When the clock signal CLK2 (FIG. 39-c) is counted to the preset values P1 and P2, respectively of the counters 43 and 44, the first and second output pulses C1 and C2 are generated (FIGS. 39-d and -e). The first output pulse C1 sets a flip flop 45 and the second output pulse C2 resets the flip flop. This, in turn, forms a window pulse WP shown in FIG. 39-f. The window pulse WP is supplied to a gate circuit 46 as a gate pulse, and the clock signal CLK2 is fed into the address signal generator 47 in accordance with the width W1 of the window pulse WP. The clock signal CLK2, however, is a clock synchronous with the enlarged or reduced image data.
Consequently, as the address data fed into the memory 40 is generated for the duration W1, only an image data D corresponding to the duration W1, among the image data (FIG. 39-b) controlled by a horizontal direction valid signal (H-VALID) of FIG. 39-a, is written into the memory 40 (see FIG. 39-g).
For this reason, varying the preset values P1 and P2 in accordance with a magnification for enlarging or reducing operation proportionally varies the width W1 of window pulse WP, thus regulating the size of image data being written into the memory 40.
In a reducing operation, the width of window pulse WP is treated as same as that of the horizontal direction valid signal (H-VALID). In contrast, in an enlarging operation which involves increased image data, the total size of data is reduced to cope with the increase by reducing in advance the width of the window pulse WP in relation to the width of the horizontal direction valid signal (H-VALID).
Incidentally, the above mentioned conventional color image processing systems have the following disadvantages.
With the similar systems having the constitution in FIG. 38, though the amount of image data being written into the memory 40 is regulated in accordance with an enlarging or reducing magnification, the first address (0th address) is, regardless of the magnification, always designated the initial writing address. This may cause the image to be recorded off the transfer area of an recording paper, if such a constitution is applied, especially, to an image processing system whose reading or recording device reads or records an original draft based on the center line of an original draft or recording paper.
As shown in FIG. 40, for example, in an image processing system which reads the image data of an original draft 52 based on the center line l on a draft deck 51 and records the image based on the center line l, and when assuming W to be a maximum reading width of an image reading means, the image is recorded as shown in FIG. 41-a in an reducing operation, though the image is recorded as shown in FIG. 41-b in a same-magnification operation.
This is because the initial writing address in the memory 40, that is, the 0th address, corresponds to the initial writing position of an output device (a recording device such as a laser printer). Accordingly, if the size of a recording paper 53 to record the image is too small, the image is recorded off the transfer area of the recording paper, thus the reduced image cannot be correctly recorded on the recording paper.
If the recording paper is too large in size, there is a disadvantage too; the reduced image is recorded as shifted to one corner of the recording paper.
Furthermore, in an enlarging operation, the blank area of an original draft is also enlarged, resulting in the enlarged image shown in FIG. 41-c. This may prevent the necessary area of an image from being recorded on the recording paper 53 having a specific area.
Some of such color image processing systems have a provision which allows an operator to externally designate a recording position. These are color image processing systems which can record an enlarged image N in the designated position on a recording paper 53 shown, for example in FIG. 42-b, by enlarging an area n in an original draft 52 shown in FIG. 42-a.
With such color image processing systems, it is necessary not only to control the initial writing address of the memory 40 in compliance with a designated magnification but to control the width of horizontal direction valid signal (H-VALID) in compliance with the width of designated reading area.
As a result, the conventional color image processing systems inevitably require a complicated constitution and control of an additional circuit to designate a recording position.
Therefore, it is the object of the present invention to provide an image processing system capable of designating a recording position and accompanying a simplified constitution and control of a circuit to designate a recording position, in order to solve the above-mentioned disadvantages in the conventional systems.
Furthermore, the conventional color image processing systems, though being capable of recording a color image in compliance with an original color draft, fail to record the image whose colors are replaced with specific colors designated externally.
Externally effected arbitrary designation of colors, according to which the image is recorded, enlarges for a color image processing system the scope of application, and, accordingly, its value of utilization.
Therefore, it is the object of the invention to provide a color image processing system capable of recording specified image area in a specified color.